This invention relates to the decarbonylation of formate esters. More particularly, formate esters are decarbonylated to alcohols in the presence of a copper complex.
Decarbonylation reactions, i.e., the removal of carbon monoxide from organic carbonyl compounds, have been reviewed by Tsuji and Ohno, International Methods in Synthetic Organic Chemistry, 1, 157 (1969). Rhodium complexes can be used to convert aldehydes and acyl halides to alkanes and alkyl halides or olefins, respectively. Ruthenium complexes can also be employed for the decarbonylation of aldehydes. These reactions generally involve more complex carbonyl compounds with relatively high molecular weights as compared to simple compounds such as formaldehyde and acetaldehyde, and are typically stoichiometric in nature. Decarbonylation reactions are catalyzed by palladium metal on a support. Halpern and Kemp, J. Am. Chem. Soc., 88, 5147 (1966), report that formic acid will react with ruthenium (II) chloride in a stoichiometric decarbonylation reaction. Coffey, Chem. Comm. 923 (1967), reports that phosphine stabilized iridium and ruthenium complexes are excellent homogeneous catalysts for the decomposition of formic acid. The reaction, however, results in decarboxylation rather than decarbonylation under catalytic conditions. Pignolet and Doughty, J. Am. Chem. Soc., 100, 7083 (1978), studied the mechanism of the homogeneous catalytic decarbonylation of benzaldehyde and heptanal using rhodium complexes containing chelating phosphine ligands. Finally, Ying and Madix, J. of Catalysis, 61, 48 (1980) investigated the decarboxylation of formic acid with a metallic copper catalyst.
There is considerable interest in the selective preparation of low molecular oxygenates from synthesis gas. In practice, however, a range of products is usually obtained. Therefore, flexibility in the interconversion of products, i.e., the conversion of less valuable products to those of greater economic impact, is desirable. Within the scheme of interconvertibility of low molecular weight oxygenates, it would be useful to have a means of decarbonylating formate esters such as methyl formate.